HANAMAULU, Kauai » Beach closures and water advisory days were down 36 percent across the state in 2007 compared with 2006, which had unusually heavy rains in the spring, a report by the Natural Resources Defense Council says.

Dirtiest Isle Beaches

Ranking of most polluted state beaches based on the frequency that their water samples exceeded state standards on bacteria. The number is the percentage of samples over state standards:

Kauai

Hanamaulu Beach Park, 82%

Poipu Beach Park, 47%

Beach House Beach, 33%

Oahu

Keehi Lagoon, 62%

Punaluu Beach Park, 50%

Kaalawai Beach Park, 41%

Kawaikui Beach Park, 35%

Haleiwa Beach Park, 33%

Big Island

Old Kona Airport (Pawai), 36%

The state stepped up issuing advisories when heavy rains hit. The "brown water advisories," which count in the NRDC report as warnings or closures, made up 99 percent of all closures around the state last year.

Still, that number was down from 6,507 warnings issued in 2006 to 4,116 warnings in 2007. In spring 2006, Hawaii was hit by 42 straight days of rain.

In 2007, according to the report, only 40 warnings were issued for possible bacteria contamination due to sewage spills, compared with 166 sewage spills in 2006.

However, one Kauai beach made it to the top 10 of most polluted beaches in the country, according to the 18th annual report, "Testing the Waters," put out by the NRDC, a nonprofit environmental action group.

Hanamaulu Beach Park, a Kauai County park where the Hanamaulu Stream empties into the bay, was tested 22 times last year by the state Department of Health, and 19 times it exceeded state levels for two types of bacteria found in the digestive tract of humans and other mammals.

Hanamaulu was also ranked in a tie for 10th nationally as far as percentage of samples that exceeded the national levels, according to the NRDC report.

The Health Department "needs to find out why it's being so polluted ... and fix it," said Carl Berg, a Kauai biologist and former water monitor for the state.

At least the beach park is being tested -- in 2006, it was not even on the NRDC list.

"We have been increasing the number of beaches and the frequency" with which testing occurs, said Janice Okubo, Health Department spokeswoman. More federal funding has helped send monitors to the beaches, she added.

The department monitored 449 beaches statewide in 2007 compared with 131 in 2006, according to the report.

Kauai's Poipu Beach Park, frequently on lists as one of the top 10 beaches in America, had nearly 50 percent of its 82 samples above the state pollution levels in 2007. However, only 1 percent of the 82 samples taken in 2006 showed bacteria levels above the state threshold.

The 2007 levels mean that tourists have nearly a "50/50 chance" that every time people go to Poipu Beach, they will be swimming in pollutants, Berg said.

"The DOH is doing good work" in identifying problem areas, Berg added, but he said more needs to be done to find the source of the problems.